Net Loss Per Share (Calculation Of Net Income (Loss) Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net Loss Per Share [Abstract]
Net loss attributable to Frontier common shareholders	$ (715)	$ (80)	$ (844)	$ (320)
Less: Dividends paid on unvested restricted stock awards	(1)	(1)	(2)	(2)
Total basic net loss attributable to Frontier common shareholders	(716)	(81)	(846)	(322)
Effect of loss related to dilutive stock units	(2)		(2)
Total diluted net loss attributable to Frontier common shareholders	$ (718)	$ (81)	$ (848)	$ (322)
Total weighted average shares and unvested restricted stock awards outstanding - basic (in shares)	78,531	78,198	78,365	78,104
Less: Weighted average unvested restricted stock awards (in shares)	(736)	(573)	(686)	(493)
Total weighted average shares outstanding - basic (in shares)	77,795	77,625	77,679	77,611
Basic net loss per share attributable to Frontier common shareholders	$ (9.20)	$ (1.05)	$ (10.88)	$ (4.14)
Effect of dilutive shares (in shares)	156		156
Total weighted average shares outstanding - diluted (in shares)	77,951	77,625	77,835	77,611
Diluted net loss per share attributable to Frontier common shareholders	$ (9.21)	$ (1.05)	$ (10.89)	$ (4.14)